Pet exposure and risk of atopic dermatitis at the pediatric age: A meta-analysis of birth cohort studies

Background: Findings on pet exposure and the risk of atopic dermatitis (AD) in children are inconsistent. Objective: With the aim to summarize the results of exposure to different pets on AD, we undertook a meta-analysis of epidemiologic studies on this issue. Methods: In August 2012, we conducted a systematic literature search in Medline and Embase. We included analytic studies considering exposure to dogs, cats, other pets, or pets overall during pregnancy, infancy, and/or childhood, with AD assessment performed during infancy or childhood. We calculated summary relative risks and 95% CIs using both fixed- and random-effects models. We computed summary estimates across selected subgroups. Results: Twenty-six publications from 21 birth cohort studies were used in the meta-analyses. The pooled relative risks of AD for exposure versus no exposure were 0.72 (95% CI, 0.61-0.85; I² = 46%; results based on 15 studies) for exposure to dogs, 0.94 (95% CI, 0.76-1.16; I² = 54%; results based on 13 studies) for exposure to cats, and 0.75 (95% CI, 0.67-0.85; I² = 54%; results based on 11 studies) for exposure to pets overall. No heterogeneity emerged across the subgroups examined, except for geographic area. Conclusion: This meta-analysis reported a favorable effect of exposure to dogs and pets on the risk of AD in infants or children, whereas no association emerged with exposure to cats.